Fan noise or vibration when engine start up in the morning

I have started hearing some type of fan noise on my tacoma usually in the morning. it goes for like 5 minutes and then i dont think I hear any more. or maybe the noise slows down. Has any one experience this?

 

The fan runs for a bit every time you start the motor. Is that what your hearing?

 

Or the cooling fan hydraulic clutch...

 

Cooling fan, or the smog pump.

 

I think they started the smog pump for 2012.

 

No smog pump in 2010 V6. (Though the 4-cyl had it since 2005 I think.)

Since it's a TRD Off Road, what the OP may be hearing is the electric brake pressure pump. To be certain, turn the ignition key to "on" but don't start the engine. The brake pump should come on.

 

Ya... my '08 2.7 has one.
I don't notice it, but if I start up before my wife gets in, it sounds pretty bad when her door is open... she's commented a couple of times "what's wrong with your engine?", but it stops and everything quiets down/smooths out quickly.

 

Yesterday, when I started my truck at around 5:45am. It was a little chilly, the noise was loud. and it probably sounds like a fan noise. But today I left home around 7 and no noise at all.
I remember that yesterday I started the heater/defroster as soon as I started the engine. Today I didnt need to use that. but I did start the heater later and no noise. so wondering if that has something to do with it.

 

AC compressor comes on with the defroster, and if it kicks in on initial startup, it makes a heck of a noise right at the start.